Heretofore, as a cable terminal connector of this type, one constructed as shown in FIG. 5 has been known. Referring to the figure, the cable terminal connector in the prior art includes a cable terminal 20, and a porcelain jacket tube 21 which envelops the cable terminal 20, and which is filled with an insulating compound 22 such as insulating oil or insulating gas.
Here, an annular bottom metal fitting is mounted on the bottom part of the porcelain jacket tube 21, and an epoxy seat 24 is disposed concentrically with the porcelain jacket tube 21 at the lower part of the interior of this porcelain jacket tube 21. Besides, an upper metal fitting 24 and an upper covering 25 are respectively disposed at the top part of the porcelain jacket tube 21, and a conductor bar 26 is disposed concentrically with the porcelain jacket tube 21 at the upper central part of this porcelain jacket tube 21. Incidentally, the lower end part of the conductor bar 26 is located within the porcelain jacket tube 21, and the distal end part thereof is gastightly led out upwards from the central parts of the upper metal fitting 24 and the upper covering 25.
Besides, a stress cone 28 is mounted on the outer periphery of a cable insulator 27 constituting the cable terminal 20, and a conductor terminal 29 is attached to the distal end part of a cable conductor (not shown).
In the cable terminal connector of such a construction, the conductor terminal 29 is connected to that lower end part of the conductor bar 26 which is located within the porcelain jacket tube 21, and the outer surface of the stress cone 28 is held in pressed contact with the inwall surface of the epoxy seat 24.
By the way, in the figure, numeral 30 designates a pressing device which presses the stress cone 28, each of signs 31a and 31b a sealing portion, numeral 32 a clamp metal fitting, numeral 33 a mounting insulator, and numeral 34 a mounting stand.
In the cable terminal connector of such a construction, however, the connection node between the conductor terminal 29 and the conductor bar 26 exists in the interior of the porcelain jacket tube 21, and there have been drawbacks as stated below.
In the first place, there has been the drawback that, since the epoxy seat 24 for receiving the stress cone 28 exists inside the porcelain jacket tube 21, the diameter of the porcelain jacket tube 21 enlarges accordingly, resulting in the heavy weight of the porcelain jacket tube 21.
Secondly, there has been the drawback that, when the outside diameter of the porcelain jacket tube 21 enlarges, the projected cross-sectional area thereof becomes large, resulting in the degradation of the characteristic of the pollution withstand voltage of the porcelain jacket tube 21, so an elongated porcelain jacket tube must be used to meet a predetermined characteristic of pollution withstand voltage.
Thirdly, the porcelain jacket tube 21 is filled with the insulating compound 22, so that when the porcelain jacket tube 21 has broken down, the insulating compound 22 might flow out of this porcelain jacket tube 21 to cause a secondary disaster.
Fourthly, there has been the drawback that, since the components such as epoxy seat 24, upper covering 25 and clamp metal fitting 32 are required, a large number of components and a complicated structure are involved.
There has also been known a cable terminal connector wherein a polymer jacket tube is therefore used instead of the porcelain jacket tube 21 shown in FIG. 5, and wherein the polymer jacket tube is filled with an insulating oil or insulating gas. In such a cable terminal connector, however, the jacket tube is formed of a polymer being a high-molecular material, so that a water content might penetrate therethrough from outside to mix into the insulating oil or insulating gas contained in the polymer jacket tube, and to deteriorate the performance of the insulating oil or insulating gas.
Meanwhile, there has been developed a cable terminal connector wherein, as shown in FIG. 6, a cable terminal 40 is enveloped in a polymer jacket tube 41. Here, the polymer jacket tube 41 includes a conductor bar 42 which is centrally disposed, a rigid insulation sleeve 43 which is disposed on the outer periphery of the conductor bar 42, and a polymer covering 44 which is provided integrally with the outer periphery of the insulation sleeve 43.
Unlike the porcelain jacket tube, the polymer jacket tube 41 of such a construction does not include therein any epoxy seat for receiving a stress cone and need not be filled with any insulating compound, so that the structure of the polymer jacket tube 41 can be simplified, and the weight thereof can be lightened. Further, the individual portions of the polymer jacket tube 41 can be put into the form of units and transported to a site, so that the on-site execution time of this polymer jacket tube 41 can be shortened.
In the cable terminal connector employing such a polymer jacket tube, however, the connection node between the cable conductor 45 of the cable terminal 40 and the conductor bar 42 exists in the interior of the polymer jacket tube 41, and there has been the drawback that, as in the porcelain jacket tube stated before, the outside diameter of the polymer jacket tube 41 enlarges to make the weight thereof heavy. Besides, when the diameter of polymer jacket tube 41 enlarges, its projected cross-sectional area becomes large. This results in the drawback that an elongated polymer jacket tube must be used for attaining enhancement in the characteristic of pollution withstand voltage.
The present invention has been made in order to solve the drawbacks mentioned above, and it has for its object to provide a polymer jacket tube which is lighter in weight and more compact than the prior-art polymer jacket tube and which can attain the simplification of a structure, and a cable terminal connector which employs the polymer jacket tube.